This invention lies in the field of magnetic tape decks. Still more particularly, it concerns tape decks having two principal vacuum columns. Still more particularly, it concerns apparatus for automatically sequentially loading tape from tape reels into the two vacuum columns.
In tape transport devices utilizing two vacuum columns and a single capstan tape metering means, arrangements for automatically loading the vacuum columns have been a universal problem in the industry. The problem has been that as the tape reels are unreeled, allowing slack tape to drop and to cover the mouths of the two vacuum columns, it will be an impossibility to guarantee that both mouths of the two vacuum columns will be covered and sealed at exactly the same time. If they are not, then the one vacuum column that is operative will draw in the slack tape from both reels and the slack tape from the second reel will never progress downwardly to cover the mouth of the second vacuum column. This problem arises because the vacuum columns are constant tension devices and once a vacuum seal has been made at the mouth opening of one column a constant tension is set up in the tape which prevents slack tape from being freed to seal the mouth of the second column. Hence, unless both columns are sealed with the slack tape at precisely the same instant, slack tape will slip through the metering mechanism, around the capstan and into the vacuum column that has already been sealed. Since it is physically impossible to guarantee that both columns will be sealed at precisely the same time and since the mass of a short piece of tape is extremely low compared to the constant tension in the tape there is constant acceleration of tape from the second column to the first column and a slack tape does not develop, which is required to seal the second column.